Transmission of selector impulses or the like over duplexed lines



5, 1932. R. TRECHCINSKI 1,845,571

TRANSMISSION OF SELECTOR IMPULSES OR THE LIKE OVER DUPLEXED mums- FiledAug. 19, 1950 2 Sheets-Sheet l R. drech BULLS/Q1 Feb. 16, 1932. R;TRECHCINSKI 1,845,571

TRANSMISSION OF SELECTOR IMPULSES OR THE LIKE OVER DUPLEXED LINES FiledAug. 19, 1930 2 Sheets-Sheet 2 R Urea c; WS/

Patented Feb. 16, 1932 UNITED STATES :PATENT OFFICE,

ROMAN TRECHGINSKI, OF WARSAW, POLAND, ASSIG-NOB TO TELEFONAKTIEBOLAG-ETL. M. ERICS SON, 0F STOCKHOLM, SWEDEN, A COMPANY OF SWEDEN TRANSMISSIONOF SELECTOR IMPULSES OR THE LIKE OVER DUPLEXED LINES 7 Application filedAugust 19, 1930, Serial No. 476,378, and in Sweden August 20, 1929.

The transmission of selector impulses over duplexed lines is connectedwith certain diliiculties which, to a certain extent, are due to thefact that the duplexed natural lines and, in certain cases, also theduplex line formed may not be advantageously arranged in metallicconnection with theappertaining impulse sending and impulse: receivingdevices whereby thus the tra'nsmission'of direct current impulsesover-the lines is made impossible. Instead of sending rectified impulsesseparated by current interruptions over the line, an eflicient andreliable impulse sending over such lines may, however, be brought aboutaccording to the invention by adapting the impulse sender, to bringabout reversals of the current direction in a local impulse circuitwhich is inductively connected with the lines, by way of example, bymeans of an appertaining duplexing coil. The current in the localimpulse circuit will evidently be subjected to variations equal to twicethe amplitude of the current and, by the inductive connection of theimpulse circuit to the line, induction current impulses will be sentover the line of corresponding double intensity which actuate apolarized impulse relay on the receiving side.

The invention will be more closely described with reference to theaccompanying drawings on which Figure 1 diagrammatically illustrates theidea of the invention. Figure 2 shows some current diagrams and Figures3 and 4 show two embodiments of the invention.

In Figure 1 the reference character 1 denotes the impulse contact in animpulse sender, by Way of example a finger disc or a dial. The impulsecontact 1 is series connected with the winding 2 of a contact relay, thecontact set of which is arranged as a commutator or pole reversingdevice in a local intermediate circuit including the primary winding ofa transformer T, the secondary winding of which is connected to thetelephone line L. Said intermediate circuit is, in similarity with theimpulse circuit proper, open when there is no conversation going on.When the intermediate circuit is closed, the plus pole of theappertaining impulse battery is connected to the one terminal of thetransformer T over a choke coil 3-and a normally closed contact 4 in thecontact set of relay 2 whereas the minus pole is connected to theopposite terminal over a choke coil 3 and a normally closed contact 4 ofthe relay. The primary winding of the transformer is then gassed by Whencurrent in the directioniof the arrow the relay 2 is energized thecontacts 4, 4 are opened and the battery poles are instead ,con

ing, by way of example, when the subscriber lifts his microtelephone,the impulse intermediate circuit, including the primary windmg of thetransformer T, is closed. At the moment in question, which is designatedt at b in Figure 2, the current in the local circuit rises in positivedirect-ion and reachesafter a certain short period of time its fullvalue i The closing ofthe impulse circuit proper, including the relaywinding 2, may, if desired, also be causedby the lifting of thesubscribers micr-otelephone but is somewhat delayed by a suitablemechanical or electromagnetical damping device and takes this placefirst at the moment "(5 at a in Figure 2, when the current in theprimary circuit of the transqformer already has reached its full-value.In

the current closing in the intermediate circuit, a current impulse 2" at0 in Figure 2, has been sent over the line which impulse may serve toset the polarized relay inits starting position in case the relay doesnot already take up said position.

When the relay 2 at the time is energized,the current in the impulseintermediate circuit is reversed by means of the contact set in abovedescribed manner and is thus subjected to a variation equal to 21 Onaccount of the current reversal in the primary winding of thetransformer, a second impulse i of twice the amplitude of the firstimpulse is sent over the line. Said impulse may serve to initiate theselecting operation, by Way of example, by that the polarized relay,upon its shifting, actuates a pre-selector or a finder. When thesubscriber thereupon actuates his impulse sender and thereby bringsabout repeated current interruptions and closings i of short durationsat a contact 1, a series of corresponding current reversals, designatedi at b in Figure 2, are thereby caused in the intermediate circuit and acorresponding series of alternately positive and negative currentimpulses 2' at c in Figure 2, are sent over the line which impulsesshift the armature of the polarized relay 6 between its two positions.The polarized impulse relay sends then in turn corresponding selectorimpulses.

When the subscriber at the end of the conversation hooks up hismicrotelephone both the impulse circuit proper and the impulseintermediate circuit are interrupted simultaneously at the time 3 afinal impulse 2' being then sent over the line, by means of whichimpulse the polarized relay, if required, is restored to its startingposition.

In the embodiment according to Figure 8 the two telephone lines L L areduplexed in ordinary manner by means of duplexing transformers T T T Tso as to form a duplex line. Each one of the three lines is r on thesendingside provided with an impulse sending device A A and Arespectively of the kind described above and comprising a currentreversing relay 2. In the two natural lines L L the two appertainingduplexing coils T T are used also for the connection of the impulseintermediate circuit to the line and serve thus, in addition to theirordinary purpose, to replace the transformer T in Figure 1. the duplexline is connected to the line over a transformer T On the receiving sidean impulse receiving device B B or 13 respectively is connected to eachone of the lines. Said device comprises a polarized relay 6. Theconnection between the two natural lines L L and the appertainingimpulse receivers B B respectively is mediated by the correspondingduplexing transformers T T whereas the impulse receiver B for the duplexline is connected over a special transformer T The three impulsereceivers B B B are on their opposite side connected to a commonselector device C in the exchange.

The embodiment according to Figure 4 is differentiated from] that inFigure 3 only thereby that the impulse sender A and the impulse receiverB of the duplex line are directly associated with the line.v

I claim 1. A switching arrangement for the transmission of currentimpulses over phantomed lines, comprising an impulse circuit, an impulsesender controlling said circuit, a relay connected to said circuit, adirect current source, a transformer connecting said direct currentsource with the line, and means under the control of said relay forreversing the cur rent supplied to the transformer, a polarizing relaybeing provided for the reception of the induction current impulses ofalternating direction sent through the transformer upon actuation of theimpulse sender.

2. A switching arrangement as claimed in claim 1, in which said directcurrent source is connected through inductances or resistances to itscircuit including a contact set of said relay adapted to operate as apole reversing device and a primary winding of the transformer.

8. A switching arrangement as claimed in claim 1, in which is provided apole reversing device, the duplexing coils on the sending side beingadapted to transfer inductively to a main line the current impulsesreversed by the pole reversing device.

4. A switching arrangement as claimed in claim 1, inwhich the duplexingcoils on the receiving side are adapted to transfer the impulses to theappertaining polarized receiving relays.

In testimony whereof I affix my signature.

ROMAN TRECHCINSKI.

The im ulse sendin device A for

